Zenith Radio Point of Sale Display case, lighted, painted glass

This is a lighted, painted, glass , Zenith Royal 500 transistor radio Point of Sale display case. We found this in Grandpa's attic and have no idea how he acquired this case. It is 18 inches long . It is 7 1/4 inches deep at the bottom, and about 3 inches deep at the top. The logos, etc. are painted directly on the glass. Some slight chipping of the paint in areas on the top arc . The cabinet is lighted from a fixture hidden behind the painted glass. We'd certainly appreciate knowing more about this item. Thanks for your help!!